]> Dipartimento per la trasformazione digitale

gi.demarco@innovazione.gov.it

Transmute

orie@transmute.industries

Istituto Poligrafico e Zecca dello Stato

fa.marino@ipzs.it

digital credentials revocation Status Assertion is a signed object that demonstrates the validity status of a digital credential. These assertions are periodically provided to holders, who can present these to verifier along with the corresponding digital credentials. The approach outlined in this document makes the verifier able to check the non-revocation of a digital credential without requiring to query any third-party entities. About This Document The latest revision of this draft can be found at . Status information for this document may be found at . Source for this draft and an issue tracker can be found at .

Introduction Status Assertions ensure the non-revocation of digital credentials, whether in JSON Web Tokens (JWT) or CBOR Web Tokens (CWT) format. Status Assertions function similarly to OCSP Stapling (), allowing clients to present to the relying parties time-stamped assertions provided by the credential issuer. The approach outlined in this specification enables the verification of credentials against revocation without direct queries to third-party systems, enhancing privacy, reducing latency, and faciliting offline verification. The figure below illustrates the process by which a client, such as a wallet instance, requests and obtains a Status Assertion from the credential issuer. | | | Client | | Credential Issuer | | | Status Assertions | | | |<-----------------------------| | +-----------------+ +-------------------+ ]]> Figure 1: Status Assertion Issuance Flow. The figure below illustrates the process by which a client presents the Status Assertion along with the corresponding digital credential. | | +-------------------+ +----------+ ]]> Figure 2: Status Assertion Presentation Flow. In summary, the credential issuer provides the client with a Status Assertion, which is linked to a Digital Credential. This enables the client to present both the digital credential and its Status Assertion to a verifier as proof of the digital credential's validity status.

Conventions and Definitions The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 when, and only when, they appear in all capitals, as shown here.

Terminology This specification uses the terms "End-User", "Entity" as defined by OpenID Connect Core , the term "JSON Web Token (JWT)" defined by JSON Web Token (JWT) , the term "CBOR Web Token (CWT)" defined in , "Client" as defined , "Verifiable Presentation" defined in [@OpenID4VP].

Digital Credential:

A set of one or more claims about a subject made by a Credential Issuer. Alternative names are "Verifiable Credential" or "Credential".

Holder:

An entity that possesses Verifiable Credentials and has control over them to present them to the Verifiers as Verifiable Presentations.

Credential Issuer:

Entity that is responsible for the issuance of the Digital Credentials. The Issuer is responsible for the lifecycle of their issued Digital Credentials and their validity status.

Verifier:

Entity that relies on the validity of the Digital Credentials presented to it. This Entity, also known as a Relying Party, verifies the authenticity and validity of the Digital Credentials, including their revocation status, before accepting them.

Wallet Instance:

The digital Wallet in control of a User, also known as Wallet. It securely stores the User's Digital Credentials. It can present Digital Credentials to Verifiers and request Status Assertions from Issuers under the control of the User. For the purposes of this specification, the Wallet Instance is considered as a Client.

Rationale There are cases where the Verifier only needs to check the revocation status of a Digital Credential at the time of presentation, and therefore it should not be allowed to check the status of a Digital Credential over time due to some privacy constraints, in compliance with national privacy regulations. For instance, consider a scenario where a Verifier's repeated access to a status list, such as the one defined in to check the revocation status of a Digital Credential could be deemed as excessive monitoring of the End-User's activities. This could potentially infringe upon the End-User's right to privacy, as outlined in and in the the European Union's General Data Protection Regulation , by creating a detailed profile of the End-User's Digital Credential status without explicit consent for such continuous surveillance.

Requirements The general requirements for the implementation of Status Assertion are listed in this section. The Status Assertion:

• SHOULD be presented in conjunction with the Digital Credential.
• MUST include information that links it to the referenced Digital Credential;
• MUST be timestamped with its issuance datetime, using a timestamp which is at or after the time of Digital Credential issuance which it refers;
• MUST contain the expiration datetime after which the Status Assertion MUST NOT be considered valid anymore, and the Digital Credential it refers SHOULD NOT be considered valid anymore. The expiration datetime MUST be superior to the Status Assertion issuance datetime and it MUST end before the expiration datetime of the Digital Credential;
• MUST enable the offline use cases by employing validation using a cryptographic signature and the cryptographic public key of the Credential Issuer.
• MUST NOT contain personal information about the User who owns the Digital Credential to which the Status Assertion refers.

Proof of Possession of a Credential The concept of Proof of Possession (PoP) of a Credential within the framework of the Status Assertion specification encompasses a broader perspective than merely possessing the digital bytes of the Credential. It involves demonstrating rightful control or ownership over the Credential, which can manifest in various forms depending on the technology employed and the nature of the Digital Credential itself. For instance, a Digital Credential could be presented visually (de-visu) with a personal portrait serving as a binding element. While this specification does not prescribe any additional methods for the proof of possession of the Credential, it aims to offer guidance for concrete implementations utilizing common proof of possession mechanisms. This includes, but is not limited to:

1. Having the digital representation of the Digital Credential (the bytes).
2. Controlling the confirmation method of the Credential, using the Credential's cnf parameter.

The essence of requiring proof of possession over the Credential through the confirmation method, such has proving the control of the cryptographic material related to a Credential, is to ensure that the entity in possession of the Credential can execute actions exclusively reserved to the legitimate Holder. The dual-layered approach of requiring both possession of the Credential and control over it, reinforces the security and integrity of the Status Assertion process. This ensures that the Holder requesting a Status Assertion is indeed the same Holder to which the Credential was originally issued, affirming the authenticity and rightful possession of the Credential.

Status Assertion Request The following diagram shows the Wallet Instance requesting a Status Assertion to a Credential Issuer, related to a specific Credential issued by the same Credential Issuer. | | | Status Assertion Responses [...] | <--------------------------------------------------------+ | | +--------+----------+ +----------+---------+ | | | | | Wallet Instance | | Credential Issuer | | | | | +-------------------+ +--------------------+ ]]> The Wallet Instance sends the Status Assertion request to the Credential Issuer, where:

• The request MUST contain the base64url encoded hash value of the Digital Credential's Issuer signed part, such as the Issuer Signed JWT using [@SD-JWT-VC], or the Mobile Security Object using [@ISO 18013-5], for which the Status Assertion is requested, and enveloped in a signed Status Assertion Request object.
• The Status Assertion Request object MUST be signed with the private key corresponding to the confirmation claim assigned by the Issuer and contained within the Digital Credential.

The Status Assertion Request object MUST contain the parameters defined in the following table.

Header	Description	Reference
typ	It MUST be set to status-assertion-request+jwt when JWT format is used. It MUST be set to status-assertion-request+cwt when CWT format is used.	Section 4.1.1,
alg	A digital signature algorithm identifier such as per IANA "JSON Web Signature and Encryption Algorithms" registry. It MUST NOT be set to none or any symmetric algorithm (MAC) identifier.	Section 4.1.1

Payload	Description	Reference
iss	Status Assertion Request Issuer identifier. The value is supposed to be used for identifying the Wallet that has issued the request. It is out of scope for this document defining how this value should be set.	,
aud	It MUST be set with the Credential Issuer Status Assertion endpoint URL as value that identify the intended audience.	,
exp	UNIX Timestamp with the expiration time of the JWT. It MUST be superior to the value set for iat .	, ,
iat	UNIX Timestamp with the time of JWT/CWT issuance.	,
jti	Unique identifier for the JWT.	Section 4.1.7
cti	Unique identifier for the CWT.	Section 4.1.7
credential_hash	Hash value of the Digital Credential the Status Assertion is bound to.	this specification
credential_hash_alg	The Algorithm used of hashing the Digital Credential to which the Status Assertion is bound. The value SHOULD be set to sha-256.	this specification

Below is a non-normative example of a Status Assertion Request with the JWT headers and payload represented without applying signature and encoding: Below is a non-normative example of a Status Assertion Request object in CWT format represented in CBOR diagnostic notation format , where the CWT headers and payload are presented without applying signature and encoding for better readability: >, / unprotected / { }, / payload / << { / iss / 1: 0b434530-e151-4c40-98b7-74c75a5ef760 /, / aud / 3: https://issuer.example.org/status-assertion-endpoint /, / iat / 6: 1698744039 /, / exp / 4: 1698830439 /, / cti / 7: 6f204f7e-e453-4dfd-814e-9d155319408c /, / credential_hash / 8: $hash-about-MobileSecurityObject /, / credential_hash_alg / 9: sha-256 / } >>, ] ]]> Below a non-normative example representing a Status Assertion Request array with a single Status Assertion Request object in JWT format. The Status Assertion HTTP request can be sent to a single Credential Issuer regarding multiple Digital Credentials, and MUST contain a JSON object with the member status_assertion_requests. The status_assertion_requests MUST be set with an array of strings, where each string within the array represents a Digital Credential Status Assertion Request object. The Credential Issuer that receives the Status Assertion Request object MUST validate that the Wallet Instance making the request is authorized to request Status Assertions. Therefore the following requirements MUST be satisfied:

• The Credential Issuer MUST verify the compliance of all elements in the status_assertion_requests object using the confirmation method contained within the Digital Credential where the Status Assertion Request object is referred to;
• The Credential Issuer MUST verify that it is the legitimate Issuer of the Digital Credential to which each Status Assertion Request object refers.

Status Assertion Response The response MUST include a JSON object with a member named status_assertion_responses, which contains the Status Assertions and or the Status Assertion Errors related to the request made by the Wallet Instance. In the non-normative example below is represented an HTTP Response with the status_assertion_responses JSON member: The member status_assertion_responses MUST be an array of strings, where each of them represent a Status Assertion Response object, as defined in the section Status Assertion or a Status Assertion Error object, as defined in the section Status Error. For each entry in the status_assertion_responses array, the following requirements are met: - Each element in the array MUST match the corresponding element in the request array at the same position index to which it is related, eg: [requestAboutA, requestAboutB] may produce [responseAboutA, responseErrorAboutB]. - Each element MUST contain the error or the status of the assertion, using the typ member set to "status-assertion+{jwt,cwt}" or "status-assertion-error+{jwt,cwt}", depending by the object type. - The corresponding entry in the response MUST be of the same data format as requested. For example, if the entry in the request is "jwt", then the entry at the same position in the response MUST also be "jwt". - The corresponding entry in the response MUST NOT contain any information regarding the Verifier to whom it may be presented, such as the Verifier identifier as the intended audience.

Status Assertion Error If the Status Assertion is requested for a non-existent, expired, revoked or invalid Digital Credential, the Credential Issuer MUST respond with an HTTP Response with the status code set to 200 and the status_assertion_responses array with the related Status Assertion Error object. The Status Assertion Error MUST NOT be presented or provided to a Verifier, the only audience of the Status Assertion Error is the Holder of the Credential that has requested the Status Assertion. Therefore, it is not necessary that the Status Assertion Error contains the parameter aud; if present, it MUST be set to the same value as the iss parameter used by the Wallet in the corresponding Status Assertion Request object. Below a non-normative example of a Status Assertion Error object in JWT format, with the headers and payload represented in JSON and without applying the signature. The Status Assertion Error object MUST contain the parameters described in the table below:

Header	Description	Reference
typ	REQUIRED. Depending on the related Status Assertion Request object format, it MUST be set to status-assertion-error+jwt or status-assertion-error+cwt.	Section 4.1.1
alg	REQUIRED. Algorithm used to verify the cryptographic signature of the Status Assertion Error. Status Assertion Error that do not need to be signed SHOULD set the alg value to none. For further clarification about the requirement of signing the Status Assertion Errors, see Section Rationale About The Unsigned Status Assertion Errors.	Section 4.1.1

Payload	Description	Reference
iss	REQUIRED. It MUST be set to the identifier of the Issuer.	,
jti	REQUIRED. Unique identifier for the JWT.	Section 4.1.7
credential_hash	REQUIRED. The hash value MUST match the one contained in the Status Assertion Request to which the Status Assertion Error is related.	this specification
credential_hash_alg	REQUIRED. The hash algorithm MUST match the one contained in the Status Assertion Request to which the Status Assertion Error is related.	this specification
error	REQUIRED. The value SHOULD be assigned with one of the error types defined in Section 5.2 or defined in the Section Status Assertion Error Values.	Section 4.1.7
error_description	OPTIONAL. Text that clarifies the nature of the error, such as attribute changes, revocation reasons, in relation to the error value.	Section 4.1.7

Rationale About The Unsigned Status Assertion Errors To mitigate potential resource exhaustion attacks where an adversary could issue hundreds of fake Status Assertion Requests to force an Issuer to sign numerous Status Assertion Errors, it is advisable to set the header parameteralg value to none for Status Assertion Errors that do not require signatures. This approach conserves computational resources and prevents abuse, especially in scenarios where the Issuer's implementation could be vulnerable to resource exhaustion attacks. However, even if it is out of the scopes of this specification determine in which the Status Error Assertion signatures are necessary, when the Issuer signs the Status Assertion Errors the Client that received them MUST validate the signature.

Status Assertion Error Values The error parameter for the Status Assertion Error object MUST be set with one of the values defined in the table below, in addition to the values specified in :

Error Parameter Value	Description	Reference
credential_revoked	The Digital Credential results as already revoked. The reason of revocation MAY be provided in the error_description field.	this specification
credential_updated	One or more information contained in the Digital Credential are changed. The error_description field SHOULD contain a human-readable text describing the general parameters updated without specifying each one.	this specification
credential_invalid	The Digital Credential is invalid. The error_description field SHOULD contain the reason of invalidation.	this specification
invalid_request_signature	The Status Assertion Request signature validation has failed. This error type is used when the proof of possession of the Digital Credential is found not valid within the Status Assertion Request.	this specification
credential_not_found	The credential_hash value provided in the Status Assertion Request doesn't match with any active Digital Credential.	this specification
unsupported_hash_alg	The hash algorithm set in credential_hash_alg is not supported.	this specification

Status Assertion When a Status Assertion is requested to a Credential Issuer, the Issuer checks the status of the Digital Credential and creates a Status Assertion bound to it. If the Digital Credential is valid, the Credential Issuer creates a new Status Assertion, which a non-normative example is given below where the format is JWT. The Status Assertion MUST contain the parameters defined below.

Header Parameter Name	Description	Reference
alg	A digital signature algorithm identifier such as per IANA "JSON Web Signature and Encryption Algorithms" registry. It MUST NOT be set to none or to a symmetric algorithm (MAC) identifier.	,
typ	It MUST be set to status-assertion+jwt when JWT format is used. It MUST be set to status-assertion+cwt when CWT format is used.	, and this specification
kid	Unique identifier of the Credential Issuer JWK. It is required when x5c or other cryptographic public key resolution identifiers are not used.
x5c	X.509 certificate chain about the Credential Issuer. It is required when kid or other parameter are not used.

Payload Parameter Name	Description	Reference
iss	It MUST be set to the identifier of the Issuer.	,
iat	UNIX Timestamp with the time of the Status Assertion issuance.	,
exp	UNIX Timestamp with the expiration time of the JWT. It MUST be greater than the value set for iat.	, ,
credential_hash	Hash value of the Digital Credential the Status Assertion is bound to.	this specification
credential_hash_alg	The Algorithm used of hashing the Digital Credential to which the Status Assertion is bound. The value SHOULD be set to sha-256.	this specification
cnf	JSON object containing confirmation methods. The sub-member contained within cnf member, such as jwk for JWT and Cose_Key for CWT, MUST match with the one provided within the related Digital Credential. Other confirmation methods can be utilized when the referenced Digital Credential supports them, in accordance with the relevant standards.	Section 3.1, Section 3.1

Interoperability of Credential Issuers Supporting Status Assertions This section outlines how Credential Issuers support Status Assertions, detailing the necessary metadata and practices to integrate into their systems.

Credential Issuer Metadata The Credential Issuers that uses the Status Assertions MUST include in their OpenID4VCI metadata the claims:

• status_assertion_endpoint. REQUIRED. It MUST be an HTTPs URL indicating the endpoint where the Wallet Instances can request Status Assertions.
• credential_hash_alg_supported. REQUIRED. The supported Algorithm used by the Wallet Instance to hash the Digital Credential for which the Status Assertion is requested, using one of the hash algorithms listed in the .

Issued Digital Credentials The Credential Issuers that uses the Status Assertions SHOULD include in the issued Digital Credentials the object status with the JSON member status_assertion set to a JSON Object containing the following member:

• credential_hash_alg. REQUIRED. The Algorithm used of hashing the Digital Credential to which the Status Assertion is bound, using one of the hash algorithms listed in the . Among the hash algorithms, sha-256 is recommended and SHOULD be implemented by all systems.

The non-normative example of an unsecured payload of an is shown below.

Credential Issuer Implementation Considerations When the Digital Credential is issued, the Credential Issuer should calculate the hash value using the algorithm specified in status.status_assertion.credential_hash_alg and store this information in its database. This practice enhances efficiency by allowing the Credential Issuer to quickly compare the requested credential_hash with the pre-calculated one, when processing Status Assertion requests made by Holders.

Presenting Status Assertions The Wallet Instance that provides the Status Assertions using , SHOULD include in the vp_token JSON array, as defined in , the Status Assertion along with the related Digital Credential. The Verifier that receives a Digital Credential supporting the Status Assertion, SHOULD:

• Decode and validate the Digital Credential;
• Check the presence of status.status_assertion in the Digital Credential. If true, the Verifier SHOULD:
  • produce the hash of the Digital Credential using the hashing algorithm configured in status.status_assertion.credential_hash_alg;
  • decode all the Status Assertions provided in the presentation, by matching the JWS Header parameter typ set to status-assertion+jwt and looking for the credential_hash value that matches with the hash produced at the previous point;
  • evaluate the validity of the Status Assertion.

Considerations On Revocation Verification The recommendation for Verifiers to check the revocation status of Digital Credentials as a 'SHOULD' instead of a 'MUST' acknowledges that the decision to verify revocation is not absolute and may be influenced by various factors. Consider as an example the case of age-over x; even if it has expired, it may still perform its intended purpose. As a result, the expiration status alone does not render it invalid. The adaptability recognizes that the need to verify revocation status may not always coincide with the actual usability of a Digital Credential, allowing Verifiers to examine and make educated conclusions based on a variety of scenarios.

Security Considerations TODO Security

Privacy Considerations In the design and implementation of Status Assertions, particular attention has been paid to privacy considerations to ensure that the system is respectful of user privacy and compliant with relevant regulations.

Privacy Consideration: Status Assertion Request Opacity The request for a Status Assertion does not transmit the Digital Credential for which the status is being attested. Instead, it includes a proof of possession (PoP) of the Digital Credential that is only interpretable by the Credential Issuer who issued the Digital Credential for which the Status Assertion is requested. This PoP can be achieved through a cryptographic signature using the public key contained within the Digital Credential over the request. This method is essential for preventing the potential for fraudulent requests intended to mislead or disclose sensitive information to unintended parties. By separating the Digital Credential from the Status Assertion Request, the system ensures that the request does not inadvertently disclose any information about the Digital Credential or its Holder. This strategy significantly enhances the privacy and security of the system by preventing the assertion process from being used to collect information about Digital Credentials or their Holders through deceptive requests.

Privacy Consideration: Opacity of Status Assertion Content An important privacy consideration is how the Status Assertion is structured to ensure it does not reveal any information about the User or the Holder of the Digital Credential. The Status Assertion is crafted to prove only the vital information needed to verify the current state of a Digital Credential, moving beyond simple revocation or suspension checks. This is done by focusing the assertion content on the Digital Credential's present condition and the method for its verification, rather than on the identity of the Digital Credential's Holder. This approach is key in keeping the User's anonymity intact, making sure that the Status Assertion can be applied in various verification situations without risking the privacy of the people involved.

Unlinkability and Reusability of Status Assertions Status Assertions are designed to uphold privacy by allowing Verifiers to operate independently, without the need for interaction or information disclosure to third-party entities or other Verifiers. This design is pivotal in ensuring unlinkability between Verifiers, where actions taken by one Verifier cannot be correlated or linked to actions taken by another. Verifiers can directly validate the status of a Digital Credential through the Status Assertion, eliminating the need for external communication. This mechanism is key in protecting the privacy of individuals whose Digital Credentials are being verified, as it significantly reduces the risk of tracking or profiling based on verification activities across various services. While Status Assertions facilitate unlinkability, they are not inherently "single use." The specification accommodates the batch issuance of multiple Status Assertions, which can be single-use. However, particularly for offline interactions, a Single Assertion may be utilized by numerous Verifiers. This flexibility ensures that Status Assertions can support a wide range of verification scenarios, from one-time validations to repeated checks by different entities, without compromising the privacy or security of the Digital Credential Holder.

Untrackability by Digital Credential Issuers and the "Phone Home" Problem A fundamental aspect of the privacy-preserving attributes of Status Assertions is their ability to address the "phone home" problem, which is the prevention of tracking by Digital Credential Issuers. Traditional models often require Verifiers to query a central status list or contact the issuer directly, a process that can inadvertently allow Credential Issuers to track when and where a Digital Credential is verified. Status Assertions, however, encapsulate all necessary verification information within the assertion itself. This design choice ensures that Credential Issuers are unable to monitor the verification activities of their issued Digital Credentials, thereby significantly enhancing the privacy of the Holder. By removing the need for real-time communication with the Issuer for status checks, Status Assertions effectively prevent the Issuer from tracking verification activities, further reinforcing the system's dedication to protecting User privacy.

Minimization of Data Exposure The Status Assertions are designed around the data minimization principle. Data minimization ensures that only the necessary information required for the scope of attesting the non revocation status of the Digital Credential. This minimizes the exposure of potentially sensitive data.

Resistance to Enumeration Attacks The design of Status Assertions incorporates measures to resist enumeration attacks, where an adversary attempts to gather information by systematically verifying different combinations of data. By implementing robust cryptographic techniques and limiting the information contained in Status Assertions, the system reduces the feasibility of such attacks. This consideration is vital for safeguarding the privacy of the Holders and for ensuring the integrity of the verification process. Status Assertions are based on a privacy-by-design approach, reflecting a deliberate effort to balance security and privacy needs in the Digital Credential ecosystem.

IANA Considerations

JSON Web Token Claims Registration This specification requests registration of the following Claims in the IANA "JSON Web Token Claims" registry established by .

• Claim Name: credential_hash
• Claim Description: Hash value of the Digital Credential the Status Assertion is bound to.
• Change Controller: IETF
• Specification Document(s): this specification

• Claim Name: credential_hash_alg
• Claim Description: The Algorithm used of hashing the Digital Credential to which the Status Assertion is bound.
• Change Controller: IETF
• Specification Document(s): this specification

Media Type Registration This section requests registration of the following media types in the "Media Types" registry in the manner described in . To indicate that the content is a JWT-based Status Assertion:

• Type name: application
• Subtype name: status-assertion-request+jwt
• Required parameters: n/a
• Optional parameters: n/a
• Encoding considerations: binary; A JWT-based Status Assertion Request object is a JWT; JWT values are encoded as a series of base64url-encoded values (some of which may be the empty string) separated by period ('.') characters.
• Security considerations: See (#Security) of this specification
• Interoperability considerations: n/a
• Published specification: this specification
• Applications that use this media type: Applications using this specification for requesting Status Assertions.
• Fragment identifier considerations: n/a
• Additional information:
  • File extension(s): n/a
  • Macintosh file type code(s): n/a
• Person & email address to contact for further information: Giuseppe De Marco, gi.demarco@innovazione.gov.it
• Intended usage: COMMON
• Restrictions on usage: none
• Author: Giuseppe De Marco, gi.demarco@innovazione.gov.it
• Change controller: IETF
• Provisional registration? No

To indicate that the content is a CWT-based Status Assertion Request:

• Type name: application
• Subtype name: status-assertion-request+cwt
• Required parameters: n/a
• Optional parameters: n/a
• Encoding considerations: binary
• Security considerations: See (#Security) of this specification
• Interoperability considerations: n/a
• Published specification: this specification
• Applications that use this media type: Applications using this specification for requesting Status Assertions.
• Fragment identifier considerations: n/a
• Additional information:
  • File extension(s): n/a
  • Macintosh file type code(s): n/a
• Person & email address to contact for further information: Giuseppe De Marco, gi.demarco@innovazione.gov.it
• Intended usage: COMMON
• Restrictions on usage: none
• Author: Giuseppe De Marco, gi.demarco@innovazione.gov.it
• Change controller: IETF
• Provisional registration? No

To indicate that the content is a JWT-based Status Assertion:

• Type name: application
• Subtype name: status-assertion+jwt
• Required parameters: n/a
• Optional parameters: n/a
• Encoding considerations: binary
• Security considerations: See (#Security) of this specification
• Interoperability considerations: n/a
• Published specification: this specification
• Applications that use this media type: Applications using this specification for issuing or presenting Status Assertions.
• Fragment identifier considerations: n/a
• Additional information:
  • File extension(s): n/a
  • Macintosh file type code(s): n/a
• Person & email address to contact for further information: Giuseppe De Marco, gi.demarco@innovazione.gov.it
• Intended usage: COMMON
• Restrictions on usage: none
• Author: Giuseppe De Marco, gi.demarco@innovazione.gov.it
• Change controller: IETF
• Provisional registration? No

To indicate that the content is a CWT-based Status Assertion:

• Type name: application
• Subtype name: status-assertion+cwt
• Required parameters: n/a
• Optional parameters: n/a
• Encoding considerations: binary
• Security considerations: See (#Security) of this specification
• Interoperability considerations: n/a
• Published specification: this specification
• Applications that use this media type: Applications using this specification for issuing or presenting Status Assertions.
• Fragment identifier considerations: n/a
• Additional information:
  • File extension(s): n/a
  • Macintosh file type code(s): n/a
• Person & email address to contact for further information: Giuseppe De Marco, gi.demarco@innovazione.gov.it
• Intended usage: COMMON
• Restrictions on usage: none
• Author: Giuseppe De Marco, gi.demarco@innovazione.gov.it
• Change controller: IETF
• Provisional registration? No

To indicate that the content is a JWT-based Status Assertion Error:

• Type name: application
• Subtype name: status-assertion-error+jwt
• Required parameters: n/a
• Optional parameters: n/a
• Encoding considerations: binary
• Security considerations: See (#Security) of this specification
• Interoperability considerations: n/a
• Published specification: this specification
• Applications that use this media type: Applications using this specification for issuing Status Assertions Request Errors.
• Fragment identifier considerations: n/a
• Additional information:
  • File extension(s): n/a
  • Macintosh file type code(s): n/a
• Person & email address to contact for further information: Giuseppe De Marco, gi.demarco@innovazione.gov.it
• Intended usage: COMMON
• Restrictions on usage: none
• Author: Giuseppe De Marco, gi.demarco@innovazione.gov.it
• Change controller: IETF
• Provisional registration? No

To indicate that the content is a CWT-based Status Assertion Error:

• Type name: application
• Subtype name: status-assertion-error+cwt
• Required parameters: n/a
• Optional parameters: n/a
• Encoding considerations: binary
• Security considerations: See (#Security) of this specification
• Interoperability considerations: n/a
• Published specification: this specification
• Applications that use this media type: Applications using this specification for issuing Status Assertions Request Errors.
• Fragment identifier considerations: n/a
• Additional information:
  • File extension(s): n/a
  • Macintosh file type code(s): n/a
• Person & email address to contact for further information: Giuseppe De Marco, gi.demarco@innovazione.gov.it
• Intended usage: COMMON
• Restrictions on usage: none
• Author: Giuseppe De Marco, gi.demarco@innovazione.gov.it
• Change controller: IETF
• Provisional registration? No

References Normative References This second document defines the general structure of the MIME media typing system and defines an initial set of media types. [STANDARDS-TRACK] The OAuth 2.0 authorization framework enables a third-party application to obtain limited access to an HTTP service, either on behalf of a resource owner by orchestrating an approval interaction between the resource owner and the HTTP service, or by allowing the third-party application to obtain access on its own behalf. This specification replaces and obsoletes the OAuth 1.0 protocol described in RFC 5849. [STANDARDS-TRACK] This document defines procedures for the specification and registration of media types for use in HTTP, MIME, and other Internet protocols. This memo documents an Internet Best Current Practice. JSON Web Signature (JWS) represents content secured with digital signatures or Message Authentication Codes (MACs) using JSON-based data structures. Cryptographic algorithms and identifiers for use with this specification are described in the separate JSON Web Algorithms (JWA) specification and an IANA registry defined by that specification. Related encryption capabilities are described in the separate JSON Web Encryption (JWE) specification. JSON Web Encryption (JWE) represents encrypted content using JSON-based data structures. Cryptographic algorithms and identifiers for use with this specification are described in the separate JSON Web Algorithms (JWA) specification and IANA registries defined by that specification. Related digital signature and Message Authentication Code (MAC) capabilities are described in the separate JSON Web Signature (JWS) specification. A JSON Web Key (JWK) is a JavaScript Object Notation (JSON) data structure that represents a cryptographic key. This specification also defines a JWK Set JSON data structure that represents a set of JWKs. Cryptographic algorithms and identifiers for use with this specification are described in the separate JSON Web Algorithms (JWA) specification and IANA registries established by that specification. JSON Web Token (JWT) is a compact, URL-safe means of representing claims to be transferred between two parties. The claims in a JWT are encoded as a JSON object that is used as the payload of a JSON Web Signature (JWS) structure or as the plaintext of a JSON Web Encryption (JWE) structure, enabling the claims to be digitally signed or integrity protected with a Message Authentication Code (MAC) and/or encrypted. This specification describes how to declare in a JSON Web Token (JWT) that the presenter of the JWT possesses a particular proof-of- possession key and how the recipient can cryptographically confirm proof of possession of the key by the presenter. Being able to prove possession of a key is also sometimes described as the presenter being a holder-of-key. Concise Binary Object Representation (CBOR) is a data format designed for small code size and small message size. There is a need for the ability to have basic security services defined for this data format. This document defines the CBOR Object Signing and Encryption (COSE) protocol. This specification describes how to create and process signatures, message authentication codes, and encryption using CBOR for serialization. This specification additionally describes how to represent cryptographic keys using CBOR. CBOR Web Token (CWT) is a compact means of representing claims to be transferred between two parties. The claims in a CWT are encoded in the Concise Binary Object Representation (CBOR), and CBOR Object Signing and Encryption (COSE) is used for added application-layer security protection. A claim is a piece of information asserted about a subject and is represented as a name/value pair consisting of a claim name and a claim value. CWT is derived from JSON Web Token (JWT) but uses CBOR rather than JSON. This specification describes how to declare in a CBOR Web Token (CWT) (which is defined by RFC 8392) that the presenter of the CWT possesses a particular proof-of-possession key. Being able to prove possession of a key is also sometimes described as being the holder-of-key. This specification provides equivalent functionality to "Proof-of-Possession Key Semantics for JSON Web Tokens (JWTs)" (RFC 7800) but using Concise Binary Object Representation (CBOR) and CWTs rather than JavaScript Object Notation (JSON) and JSON Web Tokens (JWTs). This document defines the pushed authorization request (PAR) endpoint, which allows clients to push the payload of an OAuth 2.0 authorization request to the authorization server via a direct request and provides them with a request URI that is used as reference to the data in a subsequent call to the authorization endpoint. IANA n.d. OpenID Foundation n.d. IANA n.d. IANA n.d. IANA n.d. IANA n.d. This specification adds the equivalent of the JSON Object Signing and Encryption (JOSE) "typ" (type) header parameter to CBOR Object Signing and Encryption (COSE). This enables the benefits of explicit typing (as defined in RFC 8725, "JSON Web Token Best Current Practices") to be brought to COSE objects. The syntax of the COSE type header parameter value is the same as the existing COSE content type header parameter. n.d. In many standards track documents several words are used to signify the requirements in the specification. These words are often capitalized. This document defines these words as they should be interpreted in IETF documents. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements. RFC 2119 specifies common key words that may be used in protocol specifications. This document aims to reduce the ambiguity by clarifying that only UPPERCASE usage of the key words have the defined special meanings. Informative References n.d. n.d. n.d. MATTR Authlete Inc. Ping Identity This specification describes data formats as well as validation and processing rules to express Verifiable Credentials with JSON payloads with and without selective disclosure based on the SD-JWT [I-D.ietf-oauth-selective-disclosure-jwt] format. ISO/IEC JTC 1/SC 17 n.d. OpenID Foundation n.d. n.d.

Acknowledgments We would like to thank:

• Paul Bastien
• Sara Casanova
• Emanuele De Cupis
• Riccardo Iaconelli
• Marina Adomeit
• Victor Näslund
• Giada Sciarretta
• Amir Sharif

Document History -02

• Removed several comparisons with OAuth Status List
• Status Assertion Request and Response is now a json array with multiple entries.
• Better generalization about the confirmation methods.
• Removed any informative comparison with OAuth Status List.
• JWT and CWT typ.
• Name of the draft changed from OAuth Status Attestations to OAuth Status Assertions.
• Extended Status Assertion errors table added in the section Status Error.